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Description: Existence of a class abstraction of existentially restricted sets. Variables x and y are normally free-variable parameters in the class expression substituted for C , which can be thought of as C ( x , y ) . See comments for abrexex . (Contributed by NM, 20-Sep-2011)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | ab2rexex.1 | |- A e. _V |
|
| ab2rexex.2 | |- B e. _V |
||
| Assertion | ab2rexex | |- { z | E. x e. A E. y e. B z = C } e. _V |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | ab2rexex.1 | |- A e. _V |
|
| 2 | ab2rexex.2 | |- B e. _V |
|
| 3 | 2 | abrexex | |- { z | E. y e. B z = C } e. _V |
| 4 | 1 3 | abrexex2 | |- { z | E. x e. A E. y e. B z = C } e. _V |